1. Field of the Invention
The present invention relates generally to a method for forming a fin-shaped structure, and more specifically to a method for forming a fin-shaped structure having a taper profile.
2. Description of the Prior Art
With the increasing miniaturization of semiconductor devices, various multi-gate MOSFET devices have been developed. The multi-gate MOSFETs are advantageous for the following reasons. First, the manufacturing processes of the multi-gate MOSFET devices can be integrated into traditional logic device processes, and thus are more compatible. In addition, since the three-dimensional structure of a multi-gate MOSFET increases the overlapping area between the gate and the substrate, its channel region is controlled more effectively. This therefore reduces drain-induced barrier lowering (DIBL) effect and short channel effect. Moreover, the channel region is longer for a similar gate length. Therefore, the current between the source and the drain is increased.
However, as the size of the multi-gate MOSFETs shrink, the electrical and physical requirements in each parts of the multi-gate MOSFET become critical, like the sizes and shapes of the fin-shaped structures and the spacings between each fin-shaped structures for example. Thus, how to reach standard requirements and overcome these physical limitations has become an important issue in the industry of the multi-gate MOSFETs.